# Question #f3bdb

May 5, 2017

Alternating current $A C$ is the type of electrical current that is generated by an alternator in a car or power plant. Direct current $D C$ comes from a voltage regulator or battery.

#### Explanation:

$A C$ can be generated and used in many different forms such as sine waves that look like a swimming snake, or square waves that look like building blocks alternating above and below a center line.

Each of these waveforms start at zero potential and they gradually or suddenly jump up in the positive direction to the full potential of the force applied on them. Then the waveform gradually or suddenly returns to zero and immediately repeats the same waveform in the negative direction. This entire transition (one plus and one minus pulse) is the cycle or period of the wave, and it will continue repeating as long as the force is applied.

The sine wave has the gradual change, and the square wave has the sudden jump. Sine waves are produced by alternators in cars and power plants by the force of the car engine or the power plant turbines. Square waves are produced by inverters that can change $D C$ from batteries to $A C$ to run a building's appliances and computers in the event of a mains power failure.

$D C$ is much less exciting, with no ups and downs other than $o n \mathmr{and} o f f$. $D C$ looks like a straight line of electromotive force above a ground line or zero potential. The force behind $D C$ may be the chemical reaction occurring in a battery or the $A C$ we already generated in the car alternator. The $A C$ is then fed through diodes to strip away the waves and convert it into a nice straight line. Then we come to the voltage regulator that keeps the $D C$ voltage at a respectable level for use in the car.

You may have noticed that we changed currents from $A C \to D C$ and $D C \to A C$ in our discussion. Get used to it, because our modern machines and computers do this many times right in front of you.

You can find $A C \mathmr{and} D C$ images here: